By YUKI EDAMATSU/ Staff Writer
October 20, 2026 at 14:37 JST
The Japan Aerospace Exploration Agency (JAXA) on Oct. 20 launched a probe into space for a mission to collect and bring to Earth the first-ever samples from a Martian moon.
The MMX probe, carried into space by Japan’s flagship H3 rocket from the Tanegashima Space Center in Kagoshima Prefecture, is expected to make a roughly five-year round trip to Phobos, the larger and innermost of Mars’ two moons.
Phobos is a small celestial body about 20 to 30 kilometers in diameter.
Scientists hope to analyze sand and rocks brought back to Earth to determine if Phobos was an asteroid captured by Mars’ gravity or was formed from debris ejected from the red planet during a collision with a massive object.
The samples may also help explain how water and organic materials that can create life were delivered to Mars.
MOST POWERFUL H3 ROCKET
Against the darkness of the pre-dawn sky, the H3-24 rocket blasted off with a deafening roar at 4:41 a.m., its engine nozzles emitting a brilliant plume of flame.
The rocket is equipped with two main engines and four solid rocket boosters, giving it the most powerful configuration among H3 launch vehicles.
To escape Earth’s gravitational pull, the rocket accelerated to about 40,000 kph.
About 71 minutes after liftoff, the MMX spacecraft separated from the rocket and began its goal of completing JAXA’s Martian Moons Exploration (MMX) mission.
Although U.S. rovers have collected and analyzed rocks on Mars, which is located 55 million to 400 million kilometers from Earth, no Martian samples have been returned to Earth.
Scientists believe that material kicked up from Mars by meteorite impacts has accumulated on the surface of Phobos.
If samples collected by the MMX spacecraft contain material originating from Mars, it would be the world’s first case of a Martian sample return.
BUILT ON HAYABUSA’S TECHNOLOGY
Phobos is also targeted for use as a relay and operations base for future crewed missions to Mars.
Through MMX, researchers will study the moon’s topography, surface conditions, radiation environment and other characteristics to assess whether it could serve as a “natural space station.”
The MMX spacecraft weighed 4,480 kilograms at launch, making it the largest lunar or planetary probe ever developed by Japan.
The spacecraft was developed by Mitsubishi Electric Corp. at a cost of about 55.3 billion yen ($350 million).
It consists of three modules: an outbound module for the journey to Mars; an exploration module for observations and landing operations; and a return module for the trip back to Earth.
Parts that have completed their functions will be jettisoned in stages to reduce the spacecraft’s weight during the return journey.
The probe carries instruments provided by the United States, France, Germany and other countries, making it the largest internationally coordinated space exploration mission ever led by Japan.
The spacecraft is expected to enter orbit around Mars in August 2027.
After conducting observations of Phobos’ terrain and composition while flying near the moon, the probe will attempt two landings.
Once on the surface, it will attempt to collect more than 10 grams of samples through such methods as driving a tube into the terrain with a robotic arm.
After departing from Phobos, it will also approach and observe Mars’ other moon, Deimos.
According to the mission plans, MMX will leave the Martian system in November 2030 and begin its journey to Earth. It is expected to release a sample capsule for recovery in Australia in July 2031.
This mission represents the culmination of 40 years of Japan’s planetary exploration.
In particular, it builds on the technologies and expertise developed through the Hayabusa spacecraft, which returned particles from the asteroid Itokawa, and Hayabusa 2, which landed twice on the asteroid Ryugu and collected samples.
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An H3 rocket carrying the MMX spacecraft lifts off at the Tanegashima Space Center in Kagoshima Prefecture on Oct. 20. (Kazushige Kobayashi)
